Hey, quick question.

I need to use a 470 ohm resistor to down 12 volts to 3 volts.
my question is:

What size resistor should i be using?

1/2watt? 2 watt?

should i be looking into wirewound resistors?
i have small half watt resistors right here, but i think they
might blow up or something.

any help would be great... anything!

thanx a bunch

 

So the voltage drop on 470 ohm is 9V. The power dissipation on 470 ohm will be (9V*9V)/470, which is about 0.17 watt. So a 1/2 watt resistor would be OK.

Wirewound resistor is generally of high power rating if I remember right.

 

<ME>
Sits in class, watching
jiaxima96 teach. Learns much from lesson.
</ME>

So the formula for power dissipation and to generally tell what voltage type resistor to use is (Voltage to lose * Voltage to lose)/ resistor ohm-age.

hmm cool. i was worried for like 3 hours before i decided to try plugging it all together...

i'm attempting 3 capacitors of 10,000 uf's each, hooked up to my front dome lights... the ones for the passenger and driver. 12 volts will go into those... or 3... however i decide to hook it up. and the goto, i dunno yet, maybe 4 leds per side (driver/pass).

so far it works nice in my house.... just gotta get it all functionning in the car now.

I was lucky to find a 12 volt output transformer in my place

anywho, Thanks a bunch